How do you download a pdf of a User Guide iPadOS 13 and I also want Pages

There are no PDF versions of Apple's free online product guides.

There is only an ebook/iBook/AppleBook, like this.

iPad User Guide by Apple Inc.

https://books.apple.com/us/book/ipad-user-guide/id1464778568

The iPad User Guide for iPadOS is not available as a PDF. You can, however, download the guide within the Apple Books App. Just search for “Apple” to find all the free Apple User Guides - for iPad, iPhone, AppleTV, Pages, Numbers and Keynote.

I hope you find this helpful.